Punctuation marks are defined in Google as
punc·tu·a·tion
noun
“The marks, such as period, comma, and parentheses, are used in writing to separate sentences and their elements and to clarify meaning.”

But first, an amusing quote about punctuation marks:
“I want to change my punctuation. I long for exclamation marks, but I’m drowning in ellipses.” ― Isaac Marion, Warm Bodies.

The most important punctuation  marks in English grammar are the period, question mark, exclamation point, comma, semicolon, colon, dash, hyphen, parentheses, brackets, braces, apostrophe, quotation marks, and ellipses.
You need to know the function of each of the primary punctuation marks in order to write well in the English language.
Punctuation divides written languages into identifiable parts with the use of symbols. Punctuation also indicates how a sentence spoken, – with what emphases where, with what pauses, etc.  The use and placement, or lack of use and alternate placement, of punctuation marks (we all know about the phrase comparison  ‘Let’s eat, Grandma.’ vs ‘Let’s eat Grandma.’) can totally alter the meaning of a sentence.

how punctuation marks are used in a sentence

Punctuation marks are used in the body of the sentence, and at the end of a sentence.
These punctuation marks are found at the end of a sentence: the period, question mark, and exclamation mark.
These punctuation marks are found in the body of the sentence: comma, colon, semicolon, apostrophe, hyphen, and dash.
At both the end and in the body of the sentence, an ellipsis or suspended dot can appear.

Very often, more than one punctuation mark is used in a sentence.
“Don’t step on the newly painted patio!”

The main purpose of punctuation is to group words into grammatical patterns, so that the writer’s intended meaning is clear. The correct use of punctuation marks lends meaning, expression and conversational cues in spoken and written English.