A tourist visa to Singapore is electronic (PDF document) and is issued without personal presence. Visa validity starts from the date of issue and lasts 9 weeks. Once the visa is issued, you may enter Singapore during its validity term.
This visa gives you permission to enter Singapore but not to remain there until its expiration date. The period of stay in Singapore as per individual Visit Pass is not longer than 30 days starting from the day of entry. After that, you must either leave the country or apply for an extension of your Visit Pass (the decision to extend your stay or not is at the sole discretion of the Immigration and Checkpoints Authority of Singapore).
Important note: A Singapore tourist visa is not an immigration pass. It is a pre-entry permission for the holder of a valid visa to travel to, and seek entry, into Singapore. The grant of an immigration pass will be determined by the ICA officers at the point of entry. The period of stay granted is not tied to the validity of your visa. Possession of a valid visa does not guarantee entry into Singapore.
You can apply for a Singapore visa with RSBU Travel, including Singapore travel/visitor visas.