I was also able to the source you have quoted but I still didn't get what it meant. What does it mean in simple words? In other words, I don't get the part where it says the uncertainty in the last two digits of the value. Perhaps, you could use some simple value to help me understand the concept. Thank you
A useful number to remember is that with a normal distribution of estimates, say numerous unbiased measurements of a fixed voltage, 95% of the measurements will fall within 2 standard deviations of the mean of the measurements. The term "coefficient of variation," which is usually abbreviated as "CV," is often used as a dimensionless representation of the standard deviation. The CV is simply the standard deviation divided by the mean and expressed as a percentage of the mean. Thus, if the mean of a many measurements is 100 and the CV is 5%, one would expect 95% of the measurements to be in the range of 100 ±10, i.e., 90 to 110.
Edit: In other words, given your original post regarding Planck temperature: 1.416785(71) x 10^32 Kelvin. The claim is that the true maximum temperature has a 95% probability of being between 1.416785 x 10^32 ±0.000142 x 10^32 Kelvin (i.e., within ±2 standard deviations).