When you access Salesforce from an IP address that’s outside your company’s trusted IP range using a desktop client or the API, you need a security token to login. A security token is also required when using data loader to import/export data.
A security token is a case-sensitive alphanumeric code that you append to your password or enter in a separate field in a client application.
Steps to reset your security token 👇
Step 1 — Your Name > Your Profile
Step 2— Click on My Settings
Step 3— Click on the + > Personal
Step 4— Click on Reset Security Token
Step 5— Click on the blue button “Reset Security Token”