For account verification we have two different way either you can verify account by using phone number or by using
   email ID.

Step 1.  Select the account those are asking for verification then right click on the Instagram logo , here it will see option Details 

Step 2. Click on Details here it will show you account details  along with status of the account , if the account is success it will show SUCCESS in the status , if it is asking for verification it will show REQUIRES VERIFICATION . 

Step 3. Here you will get two option for account verification 1> Phone Verification 2> Email Verification  select any one of the option which one is easy for your account verification then click on Send Verification Code , After click on Send Verification Code it will ask you  for enter verification Code in the box

Here you need to enter six digit code that you have received in phone number , then click on verify.

Step 4. After click on Verify wait for couple of minutes your account will be verify automatically then will show SUCCESS in the status then after cancel this window.