It’s a Chinese manufactured copy of the Browning Model 1900, chambered for .32ACP. These were popular pistols in pre-WWII China, and were manufactured by a wide variety of shops and arsenals. Some, like the guns made by the major arsenals at Jinling and Shanghai, were high quality firearms and others were one-off copies made by tiny shops. As a result, markings vary from Chinese characters like this one has, to exact copies of FN markings, to random jumbles of letters.
This particular gun was made in 1919, in Shanghai (according to the writing on the grips and serial number). This was one of the foremost arms producers in China at the time. In total, Shanghai (Jiangnan Arsenal) produced 66,441 of these pistols, including 60,000 of them in 1920 (compare this to a total of about 72,000 Model 1900 pistols made by FN in Belgium). Jiangnan Arsenal also made a smaller number of Browning 1900 copies with 8″ barrels, adjustable sights, and shoulder stock cuts (but still in .32 caliber).