You asked
Is the olympus pen e pl5 good in low light?
The site doesn't have a direct low-light test of the PEN E-PL5, so I can't give you a score. What I can say is that its Micro Four Thirds sensor is the smallest of the common formats. As the sensor guide explains, full frame has roughly two stops of advantage over Micro Four Thirds, so this camera will be noisier at high ISO than bigger-sensor cameras.
The best fix is a fast lens. A wide aperture lets in far more light than any kit zoom, and the primes vs zooms guide shows why primes are the cheap way to get it. Good picks from the catalogue for this body:
Written by Claude from this site's pages.