What is the meaning of -heit?

Converts an adjective into a noun and usually denotes an abstract quality of the adjectival root. It is often equivalent to the English suffixes -ness, -th, -ty, -dom:

Converts concrete nouns into abstract nouns:

-ness, -ity, -hood; forms nouns from adjectives, denoting the abstract quality of the adjective.

-ness, -ity, -hood; forms nouns from adjectives, denoting the abstract quality of the adjective.

creates abstract nouns from adjectives

creates concrete nouns

-ness, -ity, -hood; forms nouns from adjectives, denoting the abstract quality of the adjective.

-ness, -ity, -hood; forms nouns from adjectives, denoting the abstract quality of the adjective.

Source: wiktionary.org