I agree with @michelle park 일상 means daily life.
More information here : http://hanmun.vdegenne.com/일/日/0/일상
이면 is 이다 (to be) + 면 (conditional) therefore 이면 means 'if it is'.
일상이면 means 'if it is daily life' (in a literal way). The example that gave @michelle park would be, in a literal way : 'if it is daily life where I can drink coffee, I'd be satisfied'.
September 8, 2018
I would say that :
일상이면 = 일상 + 이면
일상 means daily life
이면 ( 한다면 ) : might be translated into what if or if
For example, 커피를 마실수 있는 일상이면, 난 만족해.
If I can drink a cup of coffee in daily life, I am satisfied.