Upvote:5
The way the Catholic church (and as it happens most other Christian churches) interprets these words at the beginning of John is that John is deliberately echoing the language of Genesis. "In the beginning" in John means exactly the same as "In the beginning" in Genesis.
In Genesis we read that "In the beginning God created...". In other words the first thing that happened (in time) was that God created the universe.
In John we read that "In the beginning was the Word...". This means that at the time God created the universe there was "the Word", something that already existed at the time of creation. John goes on to explain what (or rather who) that is.