Hi @Diane Herbert welcome to the Atlassian community.
As @Trudy Claspill mentioned, their is no hard number limitations. However, the user numbers vary per the plan as shared inline:
Free: Up to 10 users
Standard/ Premium/ Enterprise: Up to 20,000 users
So, now you can imagine the number of projects and tasks you can create/ configure. Please have a caution about the storage limitations.