An equilateral triangle has a side of length 4.68m. What it is perimeter ?

Since each side is equal, just multiply by 3.

Since it is an Equilateral triangle , the three sides are all of equal length  ( the three angles are all the same 60 o ). So if one side is 4.68 m , then the other two sides are each 4.68 m. 
Hence 3 x 4.68 m = 14.04 m is the perimeter. 

Perimeter of equilateral triangle: 4.68+4.68+4.68 = 14.04 m

Equilateral means that all the sides and angles are the same.
So if one side is 4.68m then the perimeter (all three sides) is 4.68 x 3.
Which is 14.04 m

The perimeter of an equilateral triangle 
which has a side of length 4.68 m is 14.04 m.