尬聊 (ga liao) refers to having an awkward conversation!
By breaking down the word individually:
尬 comes from the word 尴尬 (gang ga) which means awkward.
聊 refers to a conversation or a talk.
Therefore, when you put it together, it is suppose to symbolise people having a conversation awkwardly. It was derived from the internet as a slang word. It is usually used in the context of perhaps work environment where you don't really want to hold a full conversation with someone but due to the environment, you are obliged to make small talk. I'm sure everyone has been in this situation before!