Tartan Twos in a major show two suited hands,
the bid major and a lower ranking suit (hence 2S can show hearts).
Also, the bid shows either weak two bid strength OR Acol two bid strength (16+HCP).
Most partnerships play them as forcing for one round, unless partner has a very weak hand (fewer than 3 HCP).
There are various responses that show no game interest opposite the acol2, game
interest opposite the weak2, and game force opposite the weak2. One version
has partner
(a) raise the suit one level with no game interest opposite a strong 2 (nor interest in game opposite weak two, obviously)
(b) bid next higher suit with game interest opposite weak two, bidding 2nt if two spades was the opening bid (game forcing if strong two)
(c) bid a new suit at the three level (or 3NT) for game force opposite a weak two (slam interest if strong two)