Closest to Estonian are the Finnish languages: first of all Finnish, but also the languages of several tiny ethnic groups living in the St Petersburg region such as Karelian, Vepsan, Ingerian, the practically extinct Livonian, and Sami (or Lapp) - the language of the reindeer people in Norway, Sweden, and Finland. Its closest well-known relative language is Finnish. Most Estonians (especially those who come from the northern part of the country) can understand quite a bit of Finnish.
963,000 speakers in Estonia, 56,000 in Russia, 20,500 in USA , 14,500 in Canada, 6,000 in Finland, 3,000 in Latvia, 1,100,000 in all countries.