What are the limits for an user to make API Calls in Salesforce?

Hi Deepak,

For Salesforce Professional and Enterprise, each organization receives a total of 1,000 API calls per user in a 24-hour period, up to a maximum of 1,000,000 API calls (for organizations with 15,000+ Salesforce licenses).

Salesforce Unlimited has a 5,000 API calls per user limit, up to a maximum of unlimited API calls.

for more detail please refer https://developer.salesforce.com/docs/atlas.en-us.salesforce_app_limits_cheatsheet.meta/salesforce_app_limits_cheatsheet/salesforce_app_limits_platform_api.htm