When on turn either play a legal card or draw a card from the stock. A legal card matches the top card on the discard pile in rank or in suit.
An eight may be played on any card and the player on turn must nominate a suit.
As an example: Once 6♣ is played the next player:
can play 6♦, 6♥ or 6♠
can play any club
can play any 8 (then must declare a suit)
can draw from the stockpile and continue their turn