This page of the Genshin Impact guide explains what the Frostbearing Tree is for, how to get rewards from it and how to improve the tree.
The Frostbearing Tree acts as Statues of the Seven. In this case, however, you may offer Crimson Agates instead of offering Anemos/Geoculuses. You will find the Frostbearing Tree in Dragonspine, a new frosty location.
Dragonspine is a dangerous land where you will encounter new enemies. In addition, the climate is not favorable for your characters since they can quickly freeze. Therefore, it is important to warm up regularly.
As far as improving the Frostbearing Tree is concerned, you will need Crimson Agates. These are red crystals that you can find all over the region, whether it's in the air, caves, or even in crates. You can upgrade the Frostbearing Tree for every 10 Crimson Agates to earn various rewards.