INT'L means international. The long number is the transaction ID.
So it seems money has been taken from your account, have you been hacked/scammed?
Report to your Bank IMMEDIATELY so they cn check an tell you what the payment was for.
Remember it could be that although you have bought something in the UK it is actually coming from a foreign company with HQ overseas for tax reasons.
you said you used the card that day - what did you buy? The account billing may be in another currency so the figures will not be what you expected for example ￡1 purchase in the UK would show up as about $1.70 USD
Hope it works out OK.
Sounds like international, but best to talk to your bank to explain.