This is the 590th most frequent Icelandic word.
selja
"Selja" means "to sell."
In this sentence, 'sel' is the conjugated form of 'selja' (to sell) in first person singular present tense, indicating the act of selling.
Ég sel bókina á góðu verði.
I sell the book at a good price.
Here, 'seldu' is the past tense conjugation for third person plural, showing completion of the sale in the past.
Þeir seldu íbúðina á eftirlaun.
They sold the apartment upon retirement.
In this example, 'selja' appears in its infinitive form, emphasizing it as the action intended to be performed.