A unit change in $X$ results in a $\beta_1$ unit change in $Y$.

A unit change in $X$ results in a $(\beta_1 \cdot 100)\%$ change in $Y$.

A $1\%$ change in $X$ results in a $\beta_1\%$ change in $Y$.

A unit change in $X$ results in a $\beta_1$ change in the log of $Y$.