Definition of function :

A function is a special type relation in which each element of the domain is paired with exactly one element of the range.

A relation with one $\"\"$ - intercept is possible.

A relation with one or more $\"\"$ - intercepts are also possible, because different $\"\"$ - values can paired to the same $\"\"$ - value.

But two different $\"\"$ - values cannot paired to the same $\"\"$ - value.

Every function have only one $\"\"$ - intercept.