There are four hidden five-letter words, and you have nine guesses to find all of them. Every guess goes on all four boards at once.
On each board, green means the letter is in that word and in the right place, amber means it's in the word but somewhere else, and grey means it isn't in that word. Once you solve a board, it stops taking guesses.
Each key is split into four corners, one per board, in the same layout as the boards on screen:
The Daily set is the same for everyone and changes at midnight UK time. Practice gives you as many extra sets as you like.