Although we don't know the exact date of the postcard, the publisher (Wall, Nichols & Co.) stopped production in 1912, so I suspect the card is from sometime between 1907 and 1912.
The signs on top of the car show Fort Street and Punahou on the front and Kalihi and Waikiki on the back. The initials on the front of the car stand for Hawaii Rapid Transit & Land Company, a company founded in 1898, which developed electric streetcar service in Honolulu. The streetcars ran at 10-minute intervals and helped to popularize Waikiki.
This was not the first streetcar service though. Hawaiian Tramways Limited had previously provided mule-drawn streetcars, starting in the 1880s. By 1942, the streetcar system had been completely replaced by buses.
Most cities the size of Honolulu currently have some sort of streetcar or light rail system. Honolulu doesn't, but it has plans for an elevated transit line, a proposal that has been fiercely debated for years. Honolulu just received approval from the Federal Transit Administration to commence construction, but opponents are suing to stop the project.
Here's the back of the card.