RS-232
serial ports are not in use any more, the new standard is usb
Standard serial ports have either 5 pins or 25 pins. Although are also serial ports, USB and PS/2 ports do not obey this rule.
RS232 is a communications protocol for electronic devices to exchange information
The ports on this splitter are standard size.
Most modern laptops lack any sort of "legacy" ports such as serial ports, let alone them having two. Some older laptops did have multiple serial ports, but there's little point in recommending one because there's no guarantee you could find one. There are options for adding serial ports to a laptop, such as a USB to serial adapter, or a PC card with additional serial ports.
Many modern laptops don't have a serial port at all. The most common serial ports on desktop computers were the old style of mouse ports that look like this picture: http://i32.tinypic.com/29vtir.jpg
These interface products turn regular USB ports into ports for serial products that can be connected to other serial components for communication uses.
No. Just the opposite.
parallel and serial port
yes
RS-232 serial ports, Parallel ports, and PS2 mouse and keyboard ports. These days, all of these functions can be handled by Universal Serial Bus (USB ) connections.
Parallel ports typically have 25 or 36 pin ports. Serial ports, by contrast, have only 9 pins. Both type of ports have two rows of pins.