WRONG
I am currently on holidays.
He is on his holidays now and will be returning to the office next week.
RIGHT
I am currently on holiday.
He is on holiday now and will be returning to the office next week.
In such examples, you should not use the phrase “on holidays” or “on my holidays”, “on her holidays” etc. Use “on holiday”, or – in American English – “on vacation”.
Only use the word “holidays” to refer to:
- more than one single holiday
This year there are three national holidays in May.
I’ll see you after the Christmas holidays.
- more than one vacation
Since 2012 I have been spending my holidays in Portugal.
I prefer spending my money on holidays than on furniture.
This is chiefly a British usage; Americans use the word “vacation”.
- school holidays
The holidays start on 6 July.
We often refer to the summer (especially August) as the “holiday period”. This phrase (or the “holidays”) can also apply to Christmas.
“Holiday” can also be used as an adjective, as in “holiday period”. Other examples are “holiday clothes”, “holiday mood”.
Less commonly, in British English “holiday” can be used as a verb:
This year we’re holidaying in Portugal.
We usually holiday in the Mediterranean.
Common Mistakes in Business English 
Thank you so much for your efforts in providing great tips for non-native English speakers. I am particularly benefiting from your posts about countability of nouns. My native language is Korean. Similar to Polish or other slavic languages, we do not have articles. Neither do we pay attention to the countability of nouns. For example, instead of saying apples, we simply say that we like apple.
Your posts on countable and non-countable nouns are really helpful!
Thanks a lot for the analysis you gave on the proper use of holiday and holidays in sentence structure. it helps me a lot.
Are these sentences right or wrong?
1.This is a photo of me about holiday in spain.
2. I am married to jonh.I met him at university in 2007.
These are the correct sentences:
1. This is a photo of me on holiday in Spain.
2. I am married to John. I met him at university in 2007.