noun
BAD : Could you help me look for an accommodation?
GOOD : Could you help me look for accommodation?
BAD : Accommodations in London are very expensive.
GOOD : Accommodation in London is very expensive.
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In British English accommodation (= a place to stay or live in) is always uncountable: 'For the first year we stayed in rented accommodation.'
In American English both accommodation and accommodations (plural) are used.