男性用お手洗いって英語でなんて言うの？

In British English we tend to say use toilet instead of bathroom or restroom. So this would be the men's/women's toilet. Often, this would be abbreviated to just 'the men's'. Can you tell me where the men's is please?

The male toilets in the UK are commonly known as 'the gents' but this phrase may not be considered suitable for a high class establishment. The word 'toilet' also may convey unsavoury imagery to the fragile guest! In that case 'gents' may be used in its full form and the word 'toilet' replaced by the word 'latrine.'

A polite phrase would be using the restroom. Also not vulgar would be lavatory or bathroom. With toilet probably the least acceptable. Visitors from different countries will all have a different name or expression

Ladies room - is for women. (female) Men's room - is for men. (male) If you are at a restaurant and want to ask where the toilet is you can simply say: Excuse me, where is the men's? Excuse me, where is the men's toilet? You can also shorten it like this for the female toilet: Excuse me, where is the ladies?

In the Uk we generally use the term 'toilet' so it would be called the 'men's toilet' although sometimes it might not be suitable so you could also say 'men's room' or 'men's restroom' to describe this

When asking specifically for a place to go for men, asking "where is the men's room?" will get you the most direct answer. You may also say, "Where is the restroom?" for a more broader response. There will most likely still be a men's room there. :)