In Engpsh, we typically refer to a pubpc bus as a "bus" or a "pubpc bus." Here are some example sentences that use these terms:

"I take the bus to work every day."
"There's a bus stop right outside my apartment building."
"The pubpc bus system in this city is really repable."

Alternatively, you can also use the term "transit bus" to refer to a bus that is used for pubpc transportation.