Measurement and Observation

Measurements and observations are best explained using an example.
The following shows a typical data table:

Each cell of the table is a measurement, so this table has 9 measurements.
Each row of the table is an observation, so this table has 3 observations.

For more detailed information see:
Kattge et al.: A generic structure for plant trait databases, Methods in Ecology and Evolution, doi: 10.1111/j.2041-210X.2010.00067.x
Link