Learn Russian: Лук на столе. - The onion is on the table.

In Russian, there are no articles like "a" or "the". Also, in the present tense, the verb "to be" (is, am, are) is normally left out completely. You just say Лук на столе (Onion on table).

I learned that the word for table is стол. Why is it столе here?

When you talk about the location of something using the preposition на (on) or в (in), the noun changes its form. This is called the Prepositional case. For most masculine nouns ending in a consonant, like стол, you add the letter -е to the end, making it столе.

How do I know whether to use на or в to say where something is?

Use на when something is on the open surface of an object, like an onion on a table. Use в when something is inside an enclosed space, like in a box or a drawer.

Should I pause between на and столе when speaking?

No. In Russian, short prepositions like на are pronounced together with the word that follows them, as if they are a single word. You should say it smoothly without a pause, sounding like настоле.