Mama dotyka mojego czoła i mówi, że drugi policzek też jest czerwony.

Because the verb dotykać/dotknąć (to touch) normally takes the genitive case in Polish.

So:

• moje czoło = my forehead in the nominative/accusative
• mojego czoła = of my forehead in the genitive

After dotyka, you need the genitive:

• Mama dotyka mojego czoła. = Mom touches my forehead.

This is one of those verbs where Polish grammar differs from English, because English simply uses a direct object, while Polish uses genitive here.

The dictionary form is czoło (forehead).

In the sentence, it appears as czoła because it is in the genitive singular:

• nominative: czoło
• genitive: czoła

So:

• czoło = forehead
• dotyka czoła = touches the forehead

Also note that czoło is a neuter noun, which is why its basic form ends in -o.

In Polish, the present tense often covers both the simple and continuous meanings that English separates.

So dotyka can mean:

• touches
• is touching

Likewise:

• mówi = says / is saying

Polish usually does not need a separate word like English is for the continuous sense.

Because in Polish, a clause introduced by że (that) is normally separated by a comma.

So:

• mówi, że... = says that...

This comma is standard Polish punctuation. Even when English might sometimes omit that, Polish still commonly uses że and places a comma before it.

Że means that.

It introduces a subordinate clause:

• Mama mówi, że drugi policzek też jest czerwony.
• Mom says that the other/second cheek is also red.

It is a very common word in Polish for reported speech and statements:

• Wiem, że... = I know that...
• Myślę, że... = I think that...
• Mówi, że... = He/She says that...

Literally, drugi means second.

But in many everyday contexts, especially with things that come in pairs, drugi often naturally means the other:

• drugi policzek = the other cheek

So in this sentence, although the literal meaning is second cheek, the natural English meaning is usually the other cheek.

Because czerwony agrees with policzek, and policzek is a masculine singular noun.

Adjectives in Polish must match the noun in:

• gender
• number
• case

Here:

• policzek = masculine singular nominative
• so the adjective must also be masculine singular nominative: czerwony

Compare:

• czerwony policzek = red cheek
• czerwona ręka = red hand
• czerwone czoło = red forehead

Because policzek is the subject of the clause:

• drugi policzek też jest czerwony
• the other cheek is also red

In Polish, after być (to be), the thing being described is usually in the nominative:

• policzek jest czerwony
• cheek is red

So:

• drugi policzek = nominative subject
• czerwony matches it in nominative

Też means also / too.

In this sentence:

• drugi policzek też jest czerwony
• the other cheek is also red

Its position is quite natural in Polish. You may see też in slightly different places depending on emphasis, for example:

• Drugi policzek też jest czerwony.
• Też drugi policzek jest czerwony. — less neutral in many contexts
• Drugi policzek jest też czerwony.

The original version is a very normal, neutral way to say it.

Polish often omits possessives like my when the meaning is obvious from context.

So:

• Mama dotyka mojego czoła... naturally means My mom touches my forehead...

You could say moja mama, but it is not always necessary. In many situations, just mama sounds more natural, especially in personal narration or family context.

Mówi is the 3rd person singular present tense of mówić (to say / to speak).

So it means:

• he says
• she says
• it says

Here it refers to Mama, so:

• Mama mówi = Mom says

A few related forms:

• mówię = I say
• mówisz = you say
• mówi = he/she says
• mówimy = we say
• mówią = they say

Yes, dotykać is the imperfective verb. Its perfective partner is dotknąć.

Very roughly:

• dotykać = to be touching / to touch in a general or ongoing sense
• dotknąć = to touch once, to make contact

In the present tense, imperfective verbs can describe what is happening now:

• Mama dotyka mojego czoła. = Mom is touching my forehead.

A perfective verb like dotknąć does not normally have a true present-tense meaning like that; its present forms usually refer to the future.

Yes. Mego is a shorter variant of mojego.

So both are grammatically possible:

• mojego czoła
• mego czoła

But mojego is usually more common and neutral in everyday speech. Mego can sound a bit more literary, poetic, or simply less common depending on context.