I enjoy learning languages and in the past few years, have been learning Spanish. A work colleague, who is either new or I have only just noticed him, calls (presumably) his partner during his lunch break in the kitchen area. We're in completely different departments and our paths have never crossed, except during lunch breaks. Even when there are others in the room, he continues his slightly louder-than-normal conversations in Spanish, loudly but not rudely. We have a fair number of bilingual colleagues and a number of visiting clients to our office but to my knowledge, we might be the only two who speak Spanish (though it is evidently his native language whereas mine is English). Our office is based in the UK.
Although I cannot understand everything he says, from what I have overheard, his conversations are often of a very personal nature. They are certainly of the type that many English speakers would find inappropriate to have in an office kitchen full of people, if he was speaking in English. I suspect this is either a cultural difference or he is assuming that nobody can understand him. I suppose it is also possible that he simply doesn't care, but I can't be certain of that.
I haven't shared this info with anyone in the office but my concern is if I do nothing, he risks embarrassing himself in front of someone more vocal than me. He would likely recognise me but we don't even know each other's names. If I directly reveal to him that I can speak Spanish, he would be similarly embarrassed, or complain that I didn't inform him sooner.
Is there a way I can introduce myself and suggest a little discretion to this colleague in such a way that minimises our embarrassment?