In-built word processing capabilities

I'm going to assume you mean "Built-in" instead of "In-built". It means "already installed". In terms of computers, it means the computer already has a work processing program in it so you don't need to buy a separate one. You can also use the term for other things. You could buy a pocket knife with a built-in can opener for example.

"In-built" is a less often used alternative to "built-in".