If "は" is used as a postpositional word functioning as an auxiliary to a main word, Japanese say "wa". for example "私は=I" say "watashi wa", "あなたは=you" say "anata wa". if "は" is used as one of some word, for example "はいしゃ=dentist" say "haisya", "はる=spring" say "haru", "ごはん=rice" say "gohan".

You've got good answers already. But just a little bit probably you may want to know about it. The は is supposed to be pronounced slightly different. Regular native speakers pronounce them just same, but if you're a professional news caster you're required to pronounce differently. I believe most people recognize them if you listen them very carefully. It's also said that we used to pronounce them differently from ancient times.

If you're talking about the particle 「は」, it is pronounced "wa", not "ha".

They are the same. They are just different transcripts, that is all. "ha" is pronounced "wa".