The first code line of code is not valid SAS syntax. If you intend it as a comment, it should start with an asterisk (*). Moreover, the code should be part of a data step, i.e. it should start with a data statement. You must also tell SAS where to get the value for LENFOL, likely with a set statement.
data myNewDataset;
set myOldDataset;
* Rescale time variable from days to years;
years = lenfol / 365.25;
run;
PG