The 1 that is all the way to the right is in the thousandths place value
the 2 is in the hundredths place value
the 1 to the right is in the tenths place value the 0 is in the ones place value.
You would say this number as “zero point one-hundred twenty-one thousandths”, or a shorter way you could say it is zero point one two one.
(I’m not exactly sure what this question was asking; if I didn’t fully answer your question, or if this didn’t make sense, feel free to add a comment.)