ひつようがある

ひつようがある means that something is necessary or required in a given situation. It is used to state that there is a need for something, often after a noun (the thing that is needed) or after a verb in its dictionary form when specifying what is needed. It is common in planning, instructions, or explanations where you indicate prerequisites, requirements, or the steps that must be taken. Note that in many everyday contexts people prefer the adjective 必要だ (necessary) rather than saying ひつようがある, but ひつようがある is useful to express a possessive-like existence of a need.