Praying in Own Language

Praying in Hebrew is preferable, even if you don't understand Hebrew.  
Note You MAY pray in your own language, but only if that is the language of the country in which you are praying.
Note If your native language is not commonly spoken in the country in which you are now present, you may not pray in that language, even if you are with a minyan. If several languages are commonly spoken in your country (such as Hebrew and English in Israel, or English and Spanish in Florida and California), you may pray in any of those languages.