a lightweight consumer electronic device that looks like a hand-held computer but instead performs specific tasks; can serve as a diary or a personal database or a telephone or an alarm clock etc.
"Her PDA helped her manage appointments, track expenses, and set daily reminders all in one compact handheld unit."
Initialism of personal digital assistant.
"She updated her pda to check the latest weather forecast before leaving home."
In plain English: A PDA is an old-fashioned handheld computer that people used to carry around before smartphones became popular.
"They were caught on camera holding hands and whispering in public, much to their friends' amusement about his pda."