Meaning of MARKER in English

MARKER

[noun] [C]I've put in some markers where I planted the seeds.She reached the 500-metre marker in record time, but she fell back in the second half of the race.(figurative) The Prime Minister's speech was a marker of a change in (= showed clearly an intention to change) government policy.(figurative) He put down a marker for (= showed clearly his intention was) April as the start of the new project.A marker (pen) is a thick pen for writing or drawing.I'll need some green and red marker pens for my talk at the sales conference.

Cambridge English vocab.      Кембриджский английский словарь.