Used informally to connect clauses or statements ("that" in a dialect)

यह

English Usage: He said tha she could join us later.

Hindi Usage: उसने कहा कि वह बाद में हमारे साथ शामिल हो सकती है।

An assertion or agreement to a statement ("that" used in informal speech)

यह

English Usage: Tha she will come to the party.

Hindi Usage: यह उसने कहा कि वह पार्टी में आएगी।

Used to modify a verb in informal speech ("that" as an affirming adverb)

तो

English Usage: You did it tha well!

Hindi Usage: तुमने यह तो अच्छा किया!