Yes, it allows your computer to use Hebrew as an input language, anywhere.  

For example if I want write a document in Word, or I want to send an e-mail, I can switch to Hebrew, and just type in Hebrew.  

Or if I want to save a file and I want to give it a Hebrew name I can switch to Hebrew and type a Hebrew name, or if I want to give a Hebrew name to a shortcut on my screen to bring me to a certain website, I can give type its name in Hebrew.  

Or if I visit a website where Hebrew is required, like for example an interactive learning website where I need to type in Hebrew, I can do so without complication, just switch my keyboard to Hebrew in that webpage and everything I type is in Hebrew.  Or on a site like this, I can just switch to Hebrew without having to look for a Hebrew keyboard application, just press the toggle button...  

ככה.. אני מקלידה בעברית עכשיו

בהצלחה

התרגום של מה?

The translation of what?

the translet is very complicated a lot of mistakes

התרגום הוא מאוד מסובך מלא טעויות

What do you mean by add hebrew to your computer? Do you mean making the keyboard able to type hebrew?