Under the Umbrella's Shade is a Domain in Sumeru's Mawtiyima Forest. It's a Dendro Monument puzzle that will unlock the Domain and reward you with a Common Chest.
How to Solve the Dendro Monument Puzzle to unlock Sumeru's Shade Domain in Genshin Impact
Start by exploring the Under the Umbrella's Shade Domain northeast of Mawtiyima Forest. There you'll find four Dendro Monuments, an Auspicious Branch, and a Dendro Boulder hidden under a large rock in the middle of the clearing. Dendrograna must be summoned by you, then attack the Dendro Boulder to reveal the fifth Dendro Monument.
If you have already attempted at the puzzle, you may reset it by randomly applying Dendro onto all Monuments until they're all deactivated. With a clean slate, apply Dendro onto the Monuments in the exact order prescribed in the above image.
If you make a mistake, you may reset the puzzle by randomly activating the Monuments until they all turn off and try again. After solving the puzzle, the rock at the center will crack, allowing the Domain to surface. Keep it moving until it becomes a Waypoint in your World Map.
Check out our How to Use the Strange Parchment in Genshin Impact Luxurious Chest Puzzle Guide to Solve another puzzle in Sumeru.