I can think of two possible concepts your teacher might be trying to hammer home.
First, as BillJ said in an initial comment, gerunds are verbs that function as nouns. Typically, an -ing is added to the infinitive verb to form the gerund.
Let's take a few random verbs – teach, jog, and eat – and try it:
- Teaching is a noble profession.
- Jogging is good for your health.
- Eating too many sweets might cause you to gain weight.
On the other hand, maybe your teacher wasn't thinking about gerunds at all. It might be surprising for a learner to realize how many English words have definitions as both nouns and verbs.
For example, consider: pin, list, drink, hold, phone, rhyme, duck, and cup. (In fact, it might be harder to think of a verb that doesn't also function as a noun than to think of one that does!)
I will use each of those words in a sentence now, first as a verb, and then as a noun:
- Pin the fabric together before sewing. Use four pins for each piece.
- List all the places we might go on vacation. After that, put your list in an envelope.
- Drink four glasses of water every day in the summer. A cold drink would be nice right now.
- Hold your partner's hand gently while you dance. The wrestler put his opponent in a hold.
- Phone your brother before you leave. Could you please answer the phone?
- The word 'phone' rhymes with 'loan'. The poet had trouble writing his last rhyme.
For these last two, I'll use both the verb and noun in the same sentence:
- You should duck if you hear the hunters shooting at a duck.
- This piece is very delicate, so please carefully cup your hands around the cup.
As an interesting footnote, other words in this answer that can be used as both a noun and verb include: hammer, jog, home, function, sentence, form, take, hand, vacation, envelope, water, dance, answer, and can. (This is not the complete list.)