Meaning of Logarithmic Trend Line

Hello Everyone

I was just curious as to the meaning of the slop in an Excel logarithmic trendline. For example, y = -0.039ln(x) + 1.6792, where x = a month (1,2,3,4,etc.). Would the -.039 be a percentage change, or rate of change, or what? I keep confusing myself so thank you in advance!