The option "Invite to folder" allows you to share folders with other pCloud users. You can control the level of access these users get, by assigning permissions. Once your invitation is accepted, the folder will also appear in Shared > Folders > My shares.
Open my.pCloud.com and log in your account
Mark a folder and click Share > Invite to folder
Enter the email address of the user you'd like to invite
Assign the permission level for the user. You can choose between View, Edit and Manage rights