The main clause (the core of the sentence) is

(Something) can help tell me (something). 

(something - subject ) can help (main verb, modal form) tell (infinitive form of the verb tell following the catenative verb "help") me (indirect object)  (something - direct object of "tell")

The first something, the subject, is 

Understanding whether a verb is the main verb or not  this is a gerund phrase BUT the direct object of the gerund "understanding" is a clause: whether a verb is the main verb or not

The second something, the direct object,  is:the subordinate clause:

 if a group of words is a clause or phrase.

For example, you look up "be" in the dictionary, and see all of its forms and declination. 

Some verbs have the property that other verbs can follow them, like a chain.

The verb help can be followed by an infinitive, and the "to" can be omitted. The infinitive is not split.

He helped me to cross the street. or He helped me cross the street.

Eddie88

“Secondly, How are you liking Brazil? ”

 This is just the present progressive tense.  

I am liking, you are liking, he is liking..