Help with Knitting Instructions

I am confused about increases.

Pattern says - Inc 1 st at each end of 3rd and every foll 5th row.

Does this mean on row 3 and then on row 5. Then on row 3 and 5 again?

Please help.

It means on rows 3 and 8, and then every 5th row after that, so it would be 3, 8, 13, 18, 23, etc.