The estimate for how many times a person blinks in a day is roughly 12,000 times. The number varies according to the person, as well as other variables.
How many hours a person spends awake, whether they blink in their sleep and how often they naturally blink are important factors that can affect the estimate. According to Suzi Gage of imascientist.org, most people blink an average of 12.5 times a minute. Adding that number to a 16 hour waking period, with no blinking for the 8 hours of sleep, will yield a total of 12,000 blinks.
According to studies done in the journal Psychological Science, blinking could be a sign of someone being less attentive. Blinking can also indicate if someone is lying.