XLR to TRS balanced cables are often needed for when, say, the place/studio you're at mostly has XLR microphone cables, and your interface has TRS socket outputs. Or just for mixer/interface/monitor speaker connections (some pro monitor speakers have only balanced XLR inputs, but many mixers only have TRS balanced output sockets).
Here's how:
XLR pin 1=TRS ground, sleeve;
XLR pin 2 (hot)=TRS tip;
XLR pin 3 (cold)=TRS ring (middle).
That's all.