This is when the company provides itself with support in the form of seasonal hiring when the number of employees in the staff during certain peak periods of its operations is insufficient. Such peak periods may coincide with the summer season or winter holidays, but can also be related to the company's internal regime.
Seasonal hiring for recruiters involves sourcing a large number of new hires on the job. Consequently, it's worth preparing for such peak dates in advance - which means the recruiter and the HR department as a whole need to know the company's plans, development strategy, and events. This is a direct link between the business plan and the team's HR plan.