Después del punto, la siguiente palabra va con mayúscula, no con minúscula.

Because de + el contracts to del in Spanish.

• después de el punto → incorrect
• después del punto → correct

This contraction happens almost always with de + el.
A similar one is a + el = al.

Here, punto means a full stop / period.

So in this sentence:

• después del punto = after the full stop / after the period

In other contexts, punto can also mean point, dot, or even stitch, depending on the situation.

The comma separates the opening time expression from the main statement.

• Después del punto, = After the period,
• la siguiente palabra va con mayúscula = the next word is capitalized

This kind of comma is common when a sentence begins with a phrase like after X, in this case, normally, etc.
In everyday writing, some short opening phrases may appear without a comma, but here the comma is completely natural and clear.

Both are possible, but they are not always used in exactly the same way.

In this sentence, la siguiente palabra is the most natural way to say the next word.

• la siguiente palabra = the next word
• la palabra siguiente can also exist, but it often sounds a bit more formal or stylistically marked

Spanish adjectives can come before or after the noun, and the position sometimes affects tone or meaning. Here, siguiente normally goes before the noun when meaning next in sequence.

Literally, va con mayúscula means something like it goes with a capital letter.

This is a very natural Spanish way to talk about spelling and capitalization.

So:

• va con mayúscula = it is written with a capital letter / it takes a capital letter
• va con minúscula = it is written in lowercase

You could also hear:

• se escribe con mayúscula
• lleva mayúscula

All of these are common.

Va is the third person singular of ir. Here it does not mean literal movement. In expressions like this, Spanish uses ir con to mean to go with or to be used with.

So:

• la siguiente palabra va con mayúscula = the next word goes with a capital letter

This sounds normal in Spanish, even though English would usually say is capitalized or is written with a capital letter.

They are opposites:

• mayúscula = uppercase / capital letter
• minúscula = lowercase / small letter

Examples:

• A is mayúscula
• a is minúscula

In this sentence:

• con mayúscula = with a capital letter
• no con minúscula = not with a lowercase letter

Because in Spanish, the expression con mayúscula / con minúscula is commonly used without an article.

So Spanish says:

• va con mayúscula
• va con minúscula

rather than:

• va con una mayúscula
• va con una minúscula

The version without the article sounds more natural when talking generally about how something is written.

Yes, but the meaning shifts slightly.

• Después del punto = after the period
  This sounds like a general rule stated in a definite way.
• Después de un punto = after a period
  Also correct, but slightly more generic or less tied to a specific rule wording.

In grammar explanations, después del punto is very natural.

Yes, basically. In both languages, the word after a full stop / period normally begins with a capital letter.

So the sentence is explaining a punctuation rule that will feel familiar to an English speaker.

That said, capitalization rules are not identical in every area of writing. For example, Spanish usually uses fewer capital letters than English in things like:

• days of the week
• months
• languages
• many nationality words

But after a punto, both languages normally use a capital letter.

Usually no. Punto specifically refers to the full stop / period.

Other punctuation marks have different names, for example:

• coma = comma
• dos puntos = colon
• punto y coma = semicolon

So in this sentence, punto is specifically the punctuation mark .

The second part adds contrast and emphasis.

• va con mayúscula already gives the rule
• no con minúscula reinforces it by explicitly rejecting the opposite option

This is a common Spanish pattern:

• X, no Y
• with X, not with Y

It makes the instruction clearer, especially in teaching or explanatory contexts.

Yes. Some very common alternatives are:

• Después del punto, la siguiente palabra se escribe con mayúscula.
• Después del punto, la siguiente palabra lleva mayúscula.
• Tras el punto, la siguiente palabra va con mayúscula.

They all mean basically the same thing.

• se escribe con mayúscula = is written with a capital letter
• lleva mayúscula = takes a capital letter
• va con mayúscula = goes with a capital letter

All are natural, though va con and lleva can sound especially idiomatic in everyday explanation.