Question

How do the non-polar hydrophobic tails/polar hydrophilic heads in phospholipid play a role in cell membrane formation?

Answer 1

Cells exist in an aqueous environment.
The hydrophilic heads of the phospholipids interact with this aqueous environment, since they are polar.

The hydrophobic ends are oriented away from this environment.
Due to this, a bilayer can be formed ( a double layered sheet formed by phospholipids where the hydrophobic end are directed inwards towards the opposite side of the aqueous environment and its hydrophilic end directed outwards)

Below is an example of a phospholipid bilayer:

This bilayer allows separation between the cell from its external environment