Show me Tell me Questions
Here is a link to the dsa website, it details all of the Show me Tell me questions that you may get asked at the begining of your Driving Test and importantly the correct answer to give to the examiner.
http://www.dsa.gov.uk/Documents/FOI/Other/IA00969P.pdf
The examiner will ask you two questions. listen to what the Examiner is asking, do they want you to tell them how to check something?, in which case you just need to explain how to check it, or are they asking you to show them how to check something? in this case you will need to physically check it. Remember if you are not sure want they would like you to do just ask them.
Here is a picture of the engine bay of a BMW 1 Series :

Remember they are not expecting you to be Mechanics, and so long as you are giving them a good explanation of how to check something you’ll do fine.