It depends on where you work. Different market segments use different tools and technologies. I know a little about the server market. Someone else will need to answer regarding mobile testing.
You will need to learn at least one programming language. Microsoft-centric shops will probably use C#. Outside of the Microsoft world, they will probably use Linux with Java, Ruby, Python, or C++.
You probably want to learn SQL. It doesn't especially matter which RDBMS you use, e.g. Oracle, SQLServer, or Postgresql.
You need to learn a version control system. There are lots of options. I recommend learning Git.