What is the meaning of -ty?

A nonproductive suffix indicating single-digit integer multiples of ten.

Alternative form of -ity, used to form abstract nouns from adjectives.

Front vowel variant of -tu

Used to form collective nouns

-ty (forms numeral terms denoting multiples of ten)

alternative form of -te

forms passive participles of simple -i, -y, -u or -ą stems (or verbs with the suffix -nąć) and causes apophony of ą->ę

Source: wiktionary.org