5月3日の文章

毎月一日は家賃を払う日です。期限厳守です。遅れる場合はハリントンさんに電話して下さい。

家賃 - rent

期限 - due date, end of the term

厳守 - strict observance

期限厳守 - common phrase for talking about an important deadline

遅れる - to be late, to become late

場合 - case, situation

電話 - phone

Translation:

The first day of every month is the day to pay rent. Be sure to remember the due date. If it's late, please call Mr. Halinton.

(We were just a day late this time...)