A staggering 28 different languages are spoken in the United Kingdom, and you would be hard pushed to name them all.
So below I have done the hard work for you!
Of course, the de facto official language is English, as the primary language spoken by 95% of the UK.
Meanwhile, Welsh is the official language of Wales and is subsequently the second most spoken language in the UK.
There are many other officially recognised minority languages, plus main foreign languages due to native speakers living within the UK, as well as four varieties of sign language and not forgetting the multitude of varying dialects across each nation.
Native languages and dialects (living indigenous in the UK) in order of number of speakers are as follows: English (which belongs to the West Germanic family) and is spoken by ~55 million people according to http://www.speakenglish.co.uk/, Welsh (belonging to the Celtic – Brythonic family), Scottish (West Germanic), British Sign Language or BSL (BANZSL – British, Australian and New Zealand Sign Language), Irish (Celtic – Goidelic), Cornish (Celtic – Brythonic) and Shelta (Mixed).
The official languages of the United Kingdom are as follows: Arabic, Bengali, British Sign Language, Cantonese, Cornish, English, French, German, Greek, Gujarati, Irish, Irish Sign Language, Italian, Kashmiri, Lowland Scots, Malayalam, Northern Ireland Sign Language, Polish, Punjabi, Russian, Saraiki, Scottish Gaelic, Sign Supported English, Southwestern Caribbean Creole, Spanish, Sylheti, Urdu and Welsh.
The Welsh Language Act 1993 set out a law ensuring that English and Welsh are treated equally across the nation of Wales and throughout the public sector. The passing of the Welsh Language (Wales) Measure 2011 further enforced this, and public sector businesses, companies and organisations are subsequently required to produce bilingual documentation and website services.
In Scotland, the Gaelic Language (Scotland) Act 2005 gave the Scottish Gaelic language its first statutory basis and the Western Isles of Scotland has a policy in place to promote the language, whilst in Northern Ireland, Irish and Ulster Scots enjoy limited use alongside English (predominantly just publicly commissioned translations).
The UK government ratified the European Charter for Regional or Minority Languages to include Cornish (Cornwall), Irish and Ulster Scots (Northern Ireland), Scots and Scottish Gaelic (Scotland) and Welsh (Wales).