Let's say you have the following files on your Terraform server.

├── required_providers.tf
├── iam (directory)
│   ├── provider.tf
│   ├── resources.tf

required_providers.tf will almost always have this.

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
    }
  }
}

Let's say provider.tf has the following. In this example, the "default" profile in /home/username/.aws/config and /home/username/.aws/credentials is being used. This assumes you have setup Terraform as described in Amazon Web Services (AWS) - Getting Started with Terraform.

provider "aws" {
  alias   = "default"
  profile = "default"
  region  = "default"
}

And resources.tf has the following to create a policy named my-policy.

resource "aws_iam_instance_profile" "my-profile" {
  name = "my-profile"
  role = "my-role"
}

The terraform plan command can be used to see what Terraform should do (create the IAM profile).

~]$ terraform plan

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # aws_iam_instance_profile.my-profile will be created
  + resource "aws_iam_instance_profile" "my-profile" {
      + arn         = (known after apply)
      + create_date = (known after apply)
      + id          = (known after apply)
      + name        = "ecs-profile"
      + name_prefix = (known after apply)
      + path        = "/"
      + role        = "my-role"
      + tags_all    = (known after apply)
      + unique_id   = (known after apply)
    }

Plan: 1 to add, 0 to change, 0 to destroy.

The terraform apply command can be used to create the IAM profile.

terraform apply