What is the present progressive form of a verb?
The Present Progressive Tense is used to show that an action is continuing at the present time.
To show continuity, it needs a verb in the present form with the participle ing.
Then to indicate the present period of time, it needs a helping verb in the present form.
is, are = helping verbs
walk ing, sleep ing, sing ing = present participle
Maria is walking in the park.
The baby is sleeping with a smile.
The children are singing the lullaby song Twinkle, Twinkle, Little Star.
I hope this helps. :)