The helping verb in the given sentence is "will be".

Explanation:
- The helping verb in a sentence is a verb that helps the main verb express tense, mood, or voice.
- In the sentence "I will be studying for my exam all night", the helping verb "will be" is used to indicate future tense and continuous aspect.
- The word "will" is a modal verb that expresses future tense, while the word "be" is a linking verb that connects the subject "I" with the present participle "studying".
- The combination of "will" and "be" helps to convey the idea that the action of studying is ongoing or continuous in the future.

Let's break down the sentence further:

Subject: "I"
- The subject of the sentence is "I", which refers to the person who will be studying.

Helping Verb: "will be"
- "Will" is a modal verb that expresses the future tense. It indicates that the action of studying will happen in the future.
- "Be" is a linking verb that connects the subject "I" with the present participle "studying". It helps to form the continuous aspect of the verb.

Main Verb: "studying"
- The main verb in the sentence is "studying", which indicates the action that the subject will be doing.
- It is in the present participle form, which is used to form the continuous aspect of verbs.

Object: "for my exam all night"
- The object of the sentence is the phrase "for my exam all night", which specifies the purpose and duration of the studying.
- It explains that the subject will be studying in order to prepare for an exam and will continue doing so throughout the night.

Overall, the helping verb "will be" in the sentence "I will be studying for my exam all night" helps to convey the future tense and continuous aspect of the action of studying.