Nouns ending in -ence are usually feminine.
The suffix forms abstract nouns, often from verbs.
Is conférence masculine or feminine?
laconférence
The rule behind it
97.6% of -ence nouns are feminine
In context
La conférence s'est terminée à cinq heures.
The conference ended at five.
Nous avons écouté sa conférence à la radio.
We listened to his lecture on the radio.
Marc a donné une conférence sur la Renaissance.
Mark gave a talk on the Renaissance.