If you need to deal with matrices Julia's built-in support for that kind of stuff is the best out of any language I've ever seen (and I've tried dozens of different languages). It's like having first-class numpy arrays without installing any third party packages, and the syntax is even more convenient than Python. The standard library is reasonably comprehensive (not quite as big as in Python or Ruby or Go, but it's usually more well-designed).

It is also an excellent language for messing about because the language and especially the REPL have tons of quality-of-life features. I often use it when I want to do something interactively (eg. inspect a data set, draw a graph, or figure out what's going on with an Unicode string, or debug some bitwise trickery).

What Julia is not great at is things where you need minimal overhead. It is performant for serious number crunching like simulations or machine learning tasks, but the runtime is quite heavy for simple scripting and command-line tools (where the JIT doesn't really get a chance to kick in).