General sense of informing:
* Ipaalam - This is the most common and general translation. It means to "make known" or "tell someone."
* Ibalita - This means to "report" or "give news."
For giving information formally:
* Ipabatid - This means to "inform officially" or "communicate formally."
* Ipahayag - This means to "declare" or "announce."
For telling someone something specific:
* Sabihin - This simply means "tell" or "say."
Examples:
* Ipaalam mo sa kanya ang balita. (Inform him of the news.)
* Ibalita mo sa akin ang nangyari. (Tell me what happened.)
* Ipabatid mo sa kanila ang desisyon. (Inform them of the decision.)
* Ipahayag mo ang iyong mga pangarap. (Declare your dreams.)
* Sabihin mo sa kanya na hindi ako pupunta. (Tell him that I won't be going.)
The best translation will depend on the specific situation and the desired nuance.