What is the meaning of Preach?

To give a sermon.

To proclaim by public discourse; to utter in a sermon or a formal religious harangue.

To advise or recommend earnestly.

To teach or instruct by preaching; to inform by preaching.

To give advice in an offensive or obtrusive manner.

A religious discourse.

Used to express strong agreement (as if encouraging somebody to continue speaking).

Source: wiktionary.org