Regarde cette affiche !

Because this sentence is in the imperative (the command form). In French, when you tell someone to do something, you usually do not include the subject pronoun.

So:

• Tu regardes cette affiche. = You are looking at / You look at this poster.
• Regarde cette affiche ! = Look at this poster!

In commands, French often drops tu, nous, or vous.

Regarde is the tu imperative form of regarder (to look at, to watch).

For -er verbs, the tu imperative usually looks like the tu present form without the final -s:

• tu regardes → Regarde !
• tu parles → Parle !
• tu écoutes → Écoute !

So regarde here means look!

Because in the tu imperative of regular -er verbs, French normally drops the final -s.

Examples:

• Tu regardes → Regarde !
• Tu fermes → Ferme !
• Tu tombes → Tombe !

A learner should know there is an important exception: the -s can come back before y or en for pronunciation and smoothness:

• Vas-y !
• Manges-en !

But in Regarde cette affiche !, there is no y or en, so it stays regarde.

Because affiche is a feminine singular noun.

French demonstrative adjectives change depending on the noun:

• ce = masculine singular before most consonants
• cet = masculine singular before a vowel or mute h
• cette = feminine singular
• ces = plural

So:

• ce livre = this book
• cet arbre = this tree
• cette affiche = this poster
• ces affiches = these posters

Since affiche is feminine, cette is required.

In French, nouns have grammatical gender, and affiche is simply one of the nouns that is feminine: une affiche.

You often learn the gender together with the noun:

• une affiche
• une voiture
• une maison

That helps you choose the right article and adjective later:

• cette affiche
• une grande affiche
• l’affiche

There is not always a perfect logic to gender, so the safest habit is to memorize nouns with un or une.

Affiche usually means a poster, a public notice, or a displayed sign.

Depending on context, it could be:

• a poster on a wall
• an advertisement
• a notice board item
• a public sign

So the English translation might vary a little depending on the situation, but poster or sign is often the closest idea.

A careful approximate pronunciation is:

ruh-GARD set ah-FEESH

A bit more naturally in French:

• Regarde ≈ ruh-gard
• cette ≈ set
• affiche ≈ a-feesh

A few pronunciation notes:

• The r in French is not the English r.
• The final -e in regarde and cette is not strongly pronounced.
• affiche ends with the sh sound, like fish.

In natural speech, it flows smoothly: Regarde cette affiche !

It is informal singular, because regarde is the imperative form used with tu.

If you were speaking:

• to one friend, child, or someone you use tu with: Regarde cette affiche !
• to one person formally or to several people: Regardez cette affiche !

So the choice depends on who you are addressing.

You would use the vous imperative:

Regardez cette affiche !

That can mean:

• Look at this poster! (said politely to one person)
• Look at this poster! (said to several people)

So:

• Regarde cette affiche ! = informal singular
• Regardez cette affiche ! = formal singular or plural

French often uses regarder when you mean look at something deliberately.

• regarder = to look at / to watch
• voir = to see

So:

• Regarde cette affiche ! = Look at this poster!
• Tu vois cette affiche ? = Do you see this poster?

In English, look and see are different, and French makes a similar distinction here.

In many cases, French ce / cet / cette / ces can mean either this or that, depending on context.

So cette affiche can mean:

• this poster
• that poster

If French really wants to emphasize the contrast, it can add -ci or -là:

• cette affiche-ci = this poster
• cette affiche-là = that poster

But in ordinary speech, just cette affiche is very common.

Because this is a command or strong prompt: Look at this poster!

In French, as in English, an exclamation mark is very natural with:

• commands
• warnings
• enthusiastic remarks

Without it, the sentence could look flatter in writing, though context still matters. Here, the exclamation mark helps show that the speaker wants someone to notice the poster right away.