Why if i try tu push array it views the length of arr? [duplicate]

I have got an aray:

arr=[["кстати", 1], ["скажем", 1], ["блин", 1], ["реально", 1], ["вообще", 1], ["допустим", 1], ["фактически", 1], ["получается", 1]]

When i try to push it:

arr.push()

It returns the length of array