Definition
BIRTHTOHHVIS2YRNO reports the number of births to visitors to this household during the past two years ("in this city/town/village or outside"). By definition, household "visitor" is a temporary status, so this question presumably encompasses visitors not currently present in the household.
The related variable BIRTHTOHHVIS2YR indicates whether there were any births to visitors to the household during the past 2 years.
The information in BIRTHTOHHVIS2YRNO is taken from the household record and applies, as a characteristic of the household, to usual household residents, not current temporary visitors. Researchers may wish to exclude current visitors using the RESIDENT variable (with visitors coded "2") when women, children, or births are the unit of analysis, and using the HHRESIDENT variable when household members are the unit of analysis.