PIC16F877A and any other microcontroller have a very limited RAM in order to store information such as sounds. This is why an external memory is needed. It is common to use memory cards like CD/MMC because they are cheap, standard and it is easy to upload information from PC.
Vinod.S used a PIC16F877Ato access MMC card. So he made a custom adapter board which also scales 5V down to 3.3V. Then connected data lines to PIC SPI interface. Other hardware include a standard 2×16 LCD and mic audio input that is amplified with simple transistor circuit. Playback is done with PWM sent through RC filter.