This question is very hard to answer. Because there are plenty of programming languages these days. Can not pick or rely on single programming language. You need to learn more than one programming language. I am listing some details i.e. my personal thought.
See below list:
So, It depends upon solution not specific programming languages. If you believe yourself as software developer then you need to learn more than one programming language.
I have learned many programming languages. But Started working in VB6 & MS-Access, then VB.Net & MS Access/SQL Server then C# & SQL Server then ASP.Net, C# & SQL Server then PHP & MySql then Wordpress and now I want to learn android or xamarin also. I even worked in FoxPro.
Hope this help