How Do I Create a List Of Values From a Two-Dimensional Table?

I have an n x m table, n (rows) are years, m (cols)are months, values are temperatures.
How can I create a vector just containing the values in the correct sequence?
E.G In
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1950 x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12
….
2021 y1 y2 y3 y4 y5 y6 y7 y8 y9 y10 y11 y12
Out
1950-01 n1
1959-02 n2
…
2021-12 m12
This should be easy no? But I can only find a complex, nested, messy function on youtube.
I wish to create a single vector as input to a graph with dates (yyyy-mm) on the x-axis and temperatures on the y-axis
Some climate sites show their data in the form I’ve described eg. https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php
Thank-you
—–
Pete