Ram, who is an engineer, works with me
ఒక ఇంజనీర్ అయిన రామ్, నాతో పనిచేస్తాడు,
Use a comma (,) before and after a clause that begins with 'who', 'which', or 'whom' and that adds extra and non-essential information to a sentence.
Here, 'Ram being an engineer' is extra information. Even if the sentence was: Ram works with me - we would have understood it.
EXCEPTION EXAMPLE: There are a number of colleges which are fulfilling their welfare duties admirably.
వారి సంక్షేమ విధులను అద్భుతంగా నిర్వర్తించే చాలా కళాశాలలు ఉన్నాయి.
EXCEPTION TO THE RULE:
Don't use a comma if the clause beginning with 'who', 'which', or 'whom' is necessary to understand the meaning of the sentence:
For example: There are a number of colleges which are fulfilling their welfare duties admirably.
Here, just saying 'There are a number of colleges' makes the sentence incomplete.