This is the 14062nd most frequent Spanish word.
tardarán
"They will take" or "They will delay."
The word 'tardarán' is in the future tense of 'tardar,' implying that the action of taking time will happen in the future.
Los paquetes tardarán varios días en llegar.
The packages will take several days to arrive.
Here 'tardarán' again is future tense, suggesting the duration of time required for the action.
Tardarán menos si usan un método de envío más rápido.
They will take less time if they use a faster shipping method.
In this context, 'tardarán' indicates the time needed for the students to adapt to the change in their schedule.