What is the meaning of -ra?

Allative singular suffix.

[+verbal noun] in order to

Forms nouns or adjectives, mostly from nominal stems.

used to make suggestions

Suffix forming adjectives from nouns.

onto, on

for, by

Collective suffix, attached to nouns or adjectives, used to form nouns: -ry, -y

Rōmaji transcription of

nominal suffix

Source: wiktionary.org