will probably take timeUsed to say that something will likely require time. 長い時間がかかるだろう means “will probably take a long time.” だろう expresses probability or an educated guess.
JA: 彼女が父親の死の悲しみから立ち直るには長い時間がかかるだろう。
EN: It will probably take her a long time to recover from the grief of her father's death.