The noun (Substantiv/Nomen) Landsleute is feminine in German. Therefore, the correct definite article in the nominative singular is die. So, you say: die Landsleute.
(compatriots)
Personen, die aus dem gleichen Land stammen.
People who come from the same country.
Ich traf viele Landsleute im Urlaub.
I met many compatriots on vacation.