Learn Polish: Ostrożność to ważna cecha. - Caution is an important trait.

It is an abstract noun derived from the adjective ostrożny (careful, cautious). By dropping the adjective ending and adding the suffix -ość, we get ostrożność (caution, carefulness). This suffix works exactly like "-ness" or "-ity" in English.

What gender is the noun ostrożność?

It is feminine. Almost all abstract nouns created with the suffix -ość are feminine. This is a very helpful rule to remember because Polish nouns ending in a consonant are usually masculine, making the -ść ending a major and predictable exception.

Why does this sentence use to instead of jest for the word "is"?

When you define one noun phrase with another, Polish often uses the pronoun to instead of the conjugated verb być (to be). Using to allows both the subject (ostrożność) and the defining phrase (ważna cecha) to stay in the basic Nominative case. If you used jest, the second part would have to change to the Instrumental case: Ostrożność jest ważną cechą.

What other meanings does the word cecha have?

While translated here as "trait" (referring to a personality trait), cecha is a versatile word that is also commonly used to mean a "feature", "characteristic", or "attribute" of a person, object, or system.