"Believes" is a verb, therefore it cannot be plural or singular.
If it was a noun, such as oranges, then it could be plural or
singular. But a verb is an action, not a thing. You would use
"believes" when talking about "he" or "she", which amounts to one
(single) person. Example: She believeS the story. Or... He believeS
the story. And then for a number of people (plural), you would use
believe. Example: They believe the story. Or... Those kids believe
the story. So basically, verbs, such as "believes", can have an "s"
added onto it, but it does not mean the verb is plural. Verbs CAN
NEVER BE plural. It will always be a singular action. Just remember
that verbs are actions. Just remember that because "Janet RUNS to
the store" (notice the added "S"), it does not mean that Janet is
running in plural ways. Now, I'm about 99.9% sure I'm right. This
is just what I know from previous grammatical knowledge and a
general knowledge of the English language. If I'm mistaken, I
apologize. I hope I could help! "Believes" is a verb, therefore it
cannot be plural or singular. If it was a noun, such as oranges,
then it could be plural or singular. But a verb is an action, not a
thing. You would use "believes" when talking about "he" or "she",
which amounts to one (single) person. Example: She believeS the
story. Or... He believeS the story. And then for a number of people
(plural), you would use believe. Example: They believe the story.
Or... Those kids believe the story. So basically, verbs, such as
"believes", can have an "s" added onto it, but it does not mean the
verb is plural. Verbs CAN NEVER BE plural. It will always be a
singular action. Just remember that verbs are actions. Just
remember that because "Janet RUNS to the store" (notice the added
"S"), it does not mean that Janet is running in plural ways. Now,
I'm about 99.9% sure I'm right. This is just what I know from
previous grammatical knowledge and a general knowledge of the
English language. If I'm mistaken, I apologize. I hope I could
help!