This is the 250th most frequent Hungarian word.
lesznek
"Lesznek" means "they will be" in English.
Here, 'lesznek' is used to indicate the future presence or activity of the children.
A gyerekek holnap kirándulni lesznek.
The children will go on a trip tomorrow.
In this context, 'lesznek' conveys an evaluation or determination of files becoming important in the future.
Ezek a fájlok lesznek a legfontosabbak a projektben.
These files will be the most important in the project.
'Lesznek' here is used twice to specify conditional future states or attributes.