Questions & Answers about Við þynnum ungplönturnar.
- Við = we
- þynnum = the verb, we thin / we thin out
- ungplönturnar = the young plants or the seedlings, functioning as the direct object
So the structure is:
subject + verb + object
That is a very normal Icelandic word order in a main clause.
Þynnum is a conjugated verb form, while þynna is the infinitive.
The infinitive is the dictionary form:
- að þynna = to thin, to thin out
In this sentence, the subject is við (we), so the verb must be in the 1st person plural present tense:
- ég þynni = I thin
- við þynnum = we thin
The ending -um is the normal present-tense ending here for we.
In this context, að þynna means to thin out plants, especially in gardening.
That is, you remove some young plants so the remaining ones have more space, light, and nutrients.
So this is not about making something abstractly thinner only; it is a very natural verb for gardening contexts.