This is the 8204th most frequent Japanese word.
差し
"差し" (sashi) means "insertion," "difference," or "offering," depending on context.
差し棒 here is 'pointing stick'; it represents a tool used for indicating something.
差し棒を使って教室の地図を指しました。
Using a pointing stick, I indicated the map in the classroom.
差 in this context signifies 'difference,' referring to the temperature variation.
朝の寒暖の差が体調に影響することがあります。
The difference in temperature in the morning can affect one's health.
差し出す meaning 'to present or submit,' indicates an action of giving or offering something.