Confidence intervals are one way that researchers report statistical significance in a study. The other is the p-value.
Deeper dive
Unlike p-values, confidence intervals report the range of possible treatment effects, rather than just the average effect. Because of this, they can be useful sources of information for health reporters. Wide confidence intervals are generally distrusted in studies, since they indicate that the treatment effect is not very precise or reproducible. Narrow confidence intervals, on the other hand, are usually a sign that the study is well done and that the effect of a drug or treatment is reliably reproduced from patient to patient.
Confidence intervals are not statistically significant if they include the value of no effect; normally, the effect of no treatment is seen in the control group, sometimes called the reference group. Typically, the control group is given the value of 1, so confidence intervals that cross the number 1 are generally not statistically significant, though there are exceptions.