This is a monument in San Francisco's Golden Gate Park to California foresters who performed an important role during World War I.
The inscription on the monument reads:
To our brethren who gave their lives
Foresters of America of California
Dedicated on Dec. 4, 1927, the monument, made of white Italian marble, was planned to serve as a fountain for people and horses. A 1951 photo from the San Francisco Historical Photograph Collection shows a small metal bowl affixed on the monument wall that may have been a water fountain, but it’s not present today. The large marble basin in the monument’s center bottom is both today and in the 1951 photo filled with plants and dirt, but may have been a horse trough earlier.
For interesting background on this monument, see: https://sfrichmondreview.com/2020/10/03/looking-back-forester-monument/