English is the most common first, or native, language spoken in Britain. Nothing surprising there. The second most common first language spoken in Britain is Polish. What that sentence means is that there is a very large number of people in Britain for whom Polish is the native language; it’s an even larger group than those with Urdu, Hindi, or other widely spoken languages.
A number of maps on this page looks at ‘second most common first languages’ in various countries across the world. English comes top of the list, with people speaking it as their native language in 55 countries. France is in second place – it’s the second most common first language in 14 countries, and Russian is in third place (13 countries). Then come Spanish (8), Creole (8), Arabic (6), Kurdish (4), Portuguese (4), Italian (3) and Quechua (3).
See the maps, the languages, and the language groups on this page.