What’s a Good Second Language to Learn After TypeScript for Backend Development?

You might want to check out Golang! It's quite nice and offers good performance. Plus, it has some similarities to TypeScript, which should help ease the transition.

Java is another solid option. There's consistently a demand for Java developers, especially in enterprise settings. I've played around with Go recently, but I haven't found it quite as enjoyable as I hoped.

Don't overlook SQL! It's incredibly useful and prevalent in backend work. If you haven't used it yet, start with SQLite to get comfortable, and then explore PostgreSQL or MySQL. It's a skill that's always in demand.

It really depends on what's popular in your area; that way, you can maximize your job opportunities. That's probably the most practical approach I can suggest.

If you're considering something that shares similarities with TypeScript, .NET is a great choice. The same lead architect is behind both TypeScript and C#, so you'll notice quite a few parallels in approach.