The Azure Cosmos DB uses RU, which stands for 'Request Unit'.

The amount of RU you use depends on how heavy your database queries are.

Pricing from the official web site
(https://azure.microsoft.com/en-us/pricing/details/cosmos-db/):

100 Autoscale RU/s, single-region write account     
€0.011/hour

100 Autoscale RU/s, single-region write account with availability zone
1.25 x €0.011/hour

100 Autoscale RU/s, single-region write account distributed across N regions
N regions x €0.011/hour

100 RU/s multi-region write (multi-master) account distributed across N regions
N regions x €0.014/hour