What problems does hledger solve ?

A good question; here's a long list of answers (which might sound like marketing).
Perhaps you have one of these problems ?

I don't have an effective accounting system, and am experiencing financial chaos, loss, or worry
(This was my situation when I started writing hledger.) I can tell you that having some kind of system to keep a record of financial activity and give clarity and insight is a huge help; it can be life-changing. hledger is one very dependable accounting tool that scales smoothly from very basic to very advanced needs. It provides structure, extensive documentation with guidance for people new to accounting, and a supportive community. It is lightweight and minimal, so you can start simply without feeling overwhelmed by complex software.

My paper-based records are too much work and hard to get insights from
You can optionally automate most data entry with hledger, by importing bank data. With a little programming you can automate many accounting tasks. And hledger provides many useful and flexible reports that give immediate insight.

My accounting spreadsheet has grown too large, too error prone, or too limiting
hledger provides a simple, expressive and widely used syntax for describing any kind of financial transaction, using standard double entry bookkeeping. It scales up to large files, provides extensive error checking, and provides very flexible reports.

My accounting software is expensive, invasive, and hard to leave
As GPLv3-licensed Free Software, hledger both is free in price, and also works to preserve your personal freedoms. It runs entirely under your control, on your private machine. You can see all of its code, and you can improve it or fix it yourself, or you can hire someone to do that. There's no lock-in, and there are multiple ways to export data, including to other Plain Text Accounting apps like Ledger, Beancount, Fava, Paisa etc.

My accounting software works only with an online connection
hledger is local software that works offline. The user manuals are also built in and viewable on any machine. The only time you might need the internet is to download bank data or to run your own hledger-web server, and these are optional.

My accounting software is opaque or unreliable, and I worry about messing up my data
Most hledger operations are read only and can't affect your data. Commands that change your files are clearly identified, and often are append-only. hledger provides extensive error checking features to prevent data errors, and the app itself is heavily tested and written in a high-assurance programming language. Best of all, plain text data files are ideal for version control. This means you can review and audit every change to your data, and undo or roll back history at any time.

My accounting software is inefficient
Perhaps it's slow to start up, or perhaps certain operations are quite tedious or slow. hledger is very lightweight and fast, starting instantly and usually producing results in a fraction of a second even on old machines. It stores data as human-readable plain text files, which means you can easily do bulk edits. The command line interface means you can turn complex operations into easy commands, or integrate it in powerful scripts.

I like the idea of Plain Text Accounting, but I am finding it hard to get started.
Perhaps you've struggled to get a productive Beancount setup. Or you weren't able to figure out how to do some things with Ledger. You are finding it too much work to produce basic financial reports at the command line. Maybe you want a GUI or TUI, that's simple to install and use. You want more up to date and complete documentation, or active chat rooms where you can get quick support. hledger aims to serve both techies and non-techies, and provides a smoother getting started experience, with standard financial reports and simple UIs that just work with no configuration needed.

My accounting software is not improving, and I would prefer a tool that's actively maintained and supported.
hledger delivers a new major release every quarter, with followup bugfix releases when needed. It's the only PTA app with active chat rooms (matrix and IRC). It's the most-used PTA app at least in some circles.