Where: The road on the left is Queen's Road East, heading west with the Peak in the background. The kerbed triangle in the foreground marks the junction with Wanchai Road, which leads off to the right.
When: The photo comes from a stereoview card, issued by the "Realistic Travels Publishers", and dedicated to:
Which suggests a date after 1910, the year of King George V's coronation. But stereoview cards were often re-printed several times over a period of years, and as the other photos in the set date from in the 1890s, that's the date I'll go with for now.
What: The Kuhlan monument  in the centre of the photo was placed here in the 1850s. It commemorated the British and American sailors who died at Kuhlan (now called Gao Lan) fighting against a fleet of Chinese pirates.
In 1934 it was relocated over the hill to the junction of Leighton Road and Morrison Hill Road. In the 1960s it was moved again to the Hong Kong Cemetery, where it stands today (the Kuhlan monument is in the middle):
Back to the main photo, and the building behind the monument. That was the old Wanchai Market , which also dated back to the 1850s. When they built the next Wanchai Market , the new building took up the space where the kerbed triangle is in this photo, which is why the monument needed to be moved.
Who: It looks as though there are roadworks underway, but I can't see any sign of the workers.
Then several people are squatting along the roadside. There's one facing us, and others in a line with their backs towards us. They have goods laid out for sale:
The other people are visiting the market, with the exception of this man on the right:
His white hat and socks identify him as a Chinese Policeman. 
As always, questions, comments & corrections welcome!
- Read more about the Kuhlan Monument in this thread.
- More photos of the old Wanchai Market.
- More photos & information about the next Wanchai market.
- The Hong Kong Police website has a picture of the old Chinese Policeman's uniform. Visit this page, and click the "Uniforms" button.