Hello @CarlosFuente, it’s very simple.
First, open SharePoint site
Next, click on Site Actions (gear icon) in the right top of the browser.
- Then go to Site Settings → Site Collection Administration.
Tip: if you don’t see Site Settings link, try Site Information → View all site Settings
- And click on the Storage Metrics page to view a list of all the sites and their sizes.
The SharePoint Storage Metrics underneath Site Collection Administration, access to your all sub-sites and libraries in SharePoint Online and gives you the information about how much storage they are consuming.
For example, in this site we can see in the right we’re using only 1 GB (255 GB free of 256 GB)
And you can see each folder is consuming what, navigating in the left folders.
Of course, above I am assuming that you know how to Open ShrePoint Site - that is automatically created for every Team created in Microsfot Teams.
If it’s not the case, and you don’t know how to open a SharePoint Site associated with your Team in TEAMS, here is the way to go: