Questions & Answers about La ŝraŭbingo estas sub la selo.
La is the Esperanto definite article, equivalent to English the. It is used here because the sentence refers to specific things: a particular ŝraŭbingo and a particular selo.
A useful point: la never changes. It stays la for singular, plural, subject, and object.
In Esperanto, nouns normally end in -o. So both ŝraŭbingo and selo are nouns.
Some related forms:
- -oj = plural
- -on = singular direct object
- -ojn = plural direct object
In this sentence, both nouns are singular, and neither one is a direct object.