Often this kind of expression (xx头) is frequently seen in literature works or in a vulgar tone, in my opinion, there is a simple way to find out it's meaning in the context:
- Modify 年头 with a definite ordinal number, e.g. 第1个年头，第2个年头，第10个，第n个年头，in such case, 年头 simply means year, the first year, the second year, etc.
- Modify 年头 with other determiners or quantifiers, such as：这（this）年头，那（that）年头，那些（those）年头，有一些（there have been some）年头了，for these cases it means an indefinite period of time, or years.
so the translations would be:
这年头：these years（pay attention that it's not 'this years' because it's talking about an indefinite period of time instead of a specific year, so you have to make it plural/unspecific in English.
这些年头：equals to 这年头，both talk about unspecific period.
那些年头：equals to 那年头
有些年头了，有好些年头了：there have been some years that ...
Also you may encounter another similar expression "这日头，这些日头，那日头，那些日头，有些日头了", what you need to do is to replace "year" with "day":
我学中文有些日头了：I have been learning Chinese for many days.
As I know, besides these two usage, there isn't 这月头、这时头，这分头，这秒头，etc.