Are there any indicators on the jammers?

You made the right choice by asking this question! There is no “Not Important” question when selecting your future jammer, who you would buy and use to deal with your issues. As for indicators, most jammers have them, at least one indicator indicating that this signal jammer is powered on and working now. But there are even more.
Signal jammers such as this have two LEDs that show working and charging operations separately. There are also other types of indicators such as this signal jammer. These LEDs are located on the top of the jammer and are separated according to which blocked bands are currently operating. Thus, their warning light is also illuminated. So, when selecting your signal jammer, carefully consider the indicators you need.