Can you connect a pair of speakers to your computer?

In general, you cannot connect a pair of speakers to a computer, because the computer's sound board does not normally include a power amplifier fit to drive a speaker.
It might be possible to drive very small speakers with a high impedance directly from a sound board's headphone output, though.

Note that most "PC Speakers" can be directly connected to a computer's audio output because the speaker itself contains a power amplifier. Strictly speaking, such a speaker is a combination of a loudspeaker and an amplifier (sometimes also called an active speaker).