。
Schedules have to be kept.
Literal
Plan [topic-は] keep-must.
守る ('to protect, guard, keep') is the verb Japanese uses for 'keeping' appointments, promises, rules, and schedules. The ~なければならない obligation form stacks a conditional negative (~なければ 'if not X') with the default ならない ('won't do, becomes unacceptable') — a literal 'if not X, it won't do.' Feels heavy in translation but is routine in Japanese.