If the letter tile turns yellow, it is in the word you are trying to spell, but you’ve put it in the wrong place.
If the letter tile is green, it appears in the word and is in the right place.
So in your next guess, you can keep your green letters, rearrange your yellow ones and add some new letters to reach the solution.
You can decide your own Wordle tactics – for example, some people have a “lucky” five-letter word to start with and use the same each day, whereas others try a different starting word each time they play.
source: express.co.uk