It's a daily hexagonal crossword puzzle where you need to fill in the hexagons with alphanumeric character sequences, so that they match the regular expressions ("RegEx") rules listed around the edges. Note that the rule must be a full match, and empty hexagons are treated as spaces.

Each rule will turn bold purplebold green when the regex is satisfied, and orangered when the regex is not satisfied. When a cell is selected, the corresponding rules along each axis will be underlined.

To traverse the puzzle, Tab and Shift-Tab can be used to progress and retreat respectively. By default, the puzzle will traverse from left to right and top to bottom. By clicking on a rule, the puzzle traversal order is updated to only traverse along the axis of the selected rule.

If hints are needed click on the lightbulb. In hint mode, any filled cells that match the desired solution will be highlighted green __ and incorrect cells will be highlighted yellow __. The puzzle will keep track of which cells were used for hints and how many hints were used.

regex101.com can be a great resource for learning regex. It has a quick reference to see what each token means, as well as a place to test regex against example strings.