How does the word "today" make sense?
Solution 1:
"To-day" comes from Old English and means "on the day" similarly to how "to-morrow" means "on the morning". You will also see "On the morrow" in older writing.
today [alternative forms: to-day (archaic)]
Etymology
Via Middle English today, from Old English tōdæġ, tō dæġe (“on [the] day”), made from tō (“at, on”) + dæġe, the dative of dæġ (“day”).
[Wiktionary]