to ripen; to mature; to become ready or finished; (of fruit and crops:) to ripen; (of something being made or built:) to be completed; (of a plan or idea:) to take shape, to come to fruition
Building blocks
valmi- → stem, from valmis (ready, ripe, finished)
-ma → ma-infinitive ending
So literally valmima means: “to become ready”
Valmima is intransitive — a thing becomes ready on its own. Add the causative -ta- and you get valmistama — to make something ready.
How to use it
What to remember
Valmima is intransitive — the thing that ripens or gets finished is the subject, in the Nominative case. There is no object, so nothing goes in the Partitive here.
Example
Meie aia õunad valmivad alles sügisel
Literally: “Our garden’s apples ripen only autumn-on”
Idiomatically: “The apples in our garden don’t ripen until autumn”
Meie - Pronoun - Genitive Singular: "our"
aia - Noun - Genitive Singular: "garden's"
õunad - Noun - Nominative Plural: "apples"
valmivad - Verb - 3rd Person Plural, Present Tense: "ripen"
alles - Adverb - Indeclinable: "only/not until"
sügisel - Noun - Adessive Singular: "in autumn"