Here's the most common general consensus.
1 refers to an aspect of the 11 or 11:11 which means for us to “pay attention.”
7 is God's/the creators number or the number of creation, safety, luck and beginning.
The numbers 1 and 7 presenting at the same time in numerology we always add to the single digit to get to the root answer meaning. 1+7=8 which is the number of infinite / infinity.
Seeing the 1 and 7 together or in a sequence typically refers to “pay attention / God or The Creator's plan / Infinity.”
Some folks can and might interpret this in the clearest possible meaning: “pay attention because you should engage in your divine mission or life purpose to participate in the creator or God's grand plan for the universe to achieve your goals and reach infinity with the creator.” This is actually the older school of thought in the general line of thinking referring to Twin Flames. Interesting stuff, no?
The OLD school of thought was: Most of the time in general, most will notice the repeating number sequences because twin flames purpose is their mission and if one does not engage in their life purpose or if one neglects their mission, eternity is harder to reach.
The CURRENT school of thought is: Twin Flames receive synchronicity - as do lots of people and we tend to notice these more often when we've gone through some type of spiritual awakening due to becoming more aware in general. Also, it's said that those in ascension will also notice more syncs in general.
Personally, I am not sure that seeing or noticing repeating numbers means necessarily anything other than a specific meaning to the person who is seeing it. This is because in the current school of thought, everyone has their own meaning or way of interpreting what they happen to receive so far as syncs are concerned.
It's also said that the universe will usually deliver messages when they are necessary.
I do this so I'll make a suggestion to you as well: One can keep track of any syncs or any messages in a small notebook, writing them down or making a quick voice memo on your phone for example. Revisiting your series of syncs, things you notice and also any of your universal messages should result in a pattern, and oftentimes a larger message can sometimes be revealed in this process.
It's my belief that just about anyone can begin to notice and also to receive universal messages, including the numerology aspect. It's said that many soulmates and twin flames will often tend to focus on romantic, earthly aspects at times, and others can sometimes find themselves to be more focused on the universal vibration and how they can improve it. Others will view these syncs as energetic expressions of their loved ones, friends, relatives, and so on. It's my take that each person will interpret their syncs as intended for them.