Does it mean "in this field/area"?
One of the people said that Apple is developing optical sensors, which involves shining a light through the skin to measure indications of glucose. Accurately detecting glucose levels has been such a challenge that one of the top experts in the space, John L. Smith, described it as "the most difficult technical challenge I have encountered in my career." The space is littered with failures, as Smith points out, but that hasn't stopped companies from continuing to attempt to crack this elusive opportunity.
Apple isn't the only technology company eyeing opportunities in the space. Verily, Google's life sciences team, is currently working on a "smart" contact lens to measure blood sugar via the eye, and it partnered up with DexCom in 2015 to develop a glucose-sensing device no bigger than a bandage.