Meiosis I = Half reduction, e.g. diploid —> haploid
Meiosis II = Mitosis, e.g. haploid —>haploid

to give an example to make it more clear:

we have a diploid cell with an allele for blue eyes and brown eyes. In meiosis 1 the DNA doubles and homologgues chromosomes come together and they separate

–> thus: blue will go to one cell (2 alleles) en brown goes to the other cell (2 alleles)

–> these cells have normal amount of DNA, but contain only 1 allele and are thus haploid.

Next, in meiosis 2, the amount of DNA halves and it’s just like a mitosis.

A simple figure to complete sdekivit’s explanation: 😉
(click the image for full-size view)

Meiosis I is the reductional division – chromosome number is reduced but not the DNA content and each chromosome has 2 chromatids.
Meiosis II the chromatids are separated and hence the DNA content also.