The small gap in Northern Spain are Basques, other gaps are the Ural guys, Finno-Ugric languages:

• The big hole in the middle is Hungarians in Hungary and Southern Slovakia
• The smaller hole a bit to the East are Hungarians in Romania, aka Szeklers
• In the North Finns in Finland and Estonians in Estonia
• Even Norther the Sámi people, they live in Finland, Norway and Sweden, but on this map they are part of the Finnish gap.

There are some Turkic language speakers as well, but they are so small, they are not visible on the map, e.g. Gagauz people in Southern Ukraine. And some part of Turkey is in geographical Europe.

There are much more gaps in European Russia, mostly other Turkic and Finno-Ugric languages. Here is a nice map showing them. And the 100s of different small languages of the Caucasus: https://en.wikipedia.org/wiki/Languages_of_the_Caucasus