It would be considered a gift.
Different countries have different tax rules for gifts, but almost all have a defined limit below gifts are tax free; this limit depends on relationship: spouse/parents/kids/siblings/etc. have typically high limits; unrelated people (friends) have a lower limit.
So depending on your relationship, it might be tax free or partly taxable.
In GB, the annual limit seems to be 3000 pounds: https://www.gov.uk/inheritance-tax/gifts. Anything above that would be taxable (for you, the gift giver, not for him, the gift recipient)
The linked government sire reads:
You can give away £3,000 worth of gifts each tax year (6 April to 5
April) without them being added to the value of your estate. This is
known as your ‘annual exemption’.
You can carry any unused annual exemption forward to the next year -
but only for one year.
It seems the 3K limit is not per person, but from an individual, i.e . I cannot gift that much to multiple people. But the carry forward 1 year might cover you.