"Tohle slovo je špatné."

[AratAndrs1]

Why "This is a bad word" not correct?

[VladaFu]

Because it is closer to "Tohle je špatné slovo."

[ion1122]

AratAndrs1, remember to distinguish between the demonstrative adjective and the demonstrative pronoun. They are different both in English and in Czech.

The Czech adjective (as here) changes form (ten/ta/to/ty, etc_ and has a noun immediately following it.

The Czech pronoun is invariable for number as well as case.

[AratAndrs1]

Köszönöm!