A command that brings an existing resource at the provider (created manually or by another tool) into Terraform state, associating it with a resource block already written in the code, without recreating it.
In Terraform Associate it's the way to "adopt" pre-existing infrastructure under Terraform management. It requires the corresponding resource block to already exist in the code (even if empty) before running the import; recent versions (1.5+) can auto-generate the HCL with generate-config-out.
terraform import is a concept that can show up on the exam. Check the full guide to see it in context.