Lamium purpureum , aka purple deadnettle. It is a cool season annual weed and relatively easy to pull out. Try and get it out before those flowers go to seed or it will be back in the fall. Any broadleaf weed herbicide will kill it as well.

It is also quite edible if you fancy that.

They're likely to be back next year but from the very well supplied soil seed bank from years of the same kinds of weeds growing in that site. Even so, you can win. The younger the plants are when you get rid of them, the easier the task will be.

If you are far enough south, it should be gone on its' own soon. A spring ephemeral here.