That is pronounced either as / ðæt / ⓘ (strong form) or / ðət / ⓘ (weak form) according to its grammatical role, with one as a demonstrative and the other as an anaphoric (referencing adverb).. Used to refer to a person, object, idea, etc.
How to use that in a sentence.. Here you will get to know how to use that as pronoun, adjective, adverb and conjunctio.