What are these tiny red spots undernath tongue don't hurt?

Normal anatomy.: They most likely are normal anatomy. Get a good friend or family member willing to let you look and using a flashlight, look at that spot in their mouth. It should look similar. If it looks completely different than your red spots, see a dentist and let him/her look.

No worry--but: If you are worried then see a dentist or oral surgeon. Sounds like normal anatomy. See someone for an exam involving palpation of the area.