1. arrive at the end or finish something difficult
we'll get through this together
To 'get through' something means to finish or complete it. Usually 'getting through' something means there was an amount of difficulty or a lot of effort involved before you managed to finish. You will hear this used in social contexts: "I didn't know how we would manage to get through it when we found out John was so sick." or in professional contexts: "It was a tough year for the agriculture sector but we managed to get through it." You can also 'get through' resources meaning to use them up. "I am surprised we got through so much paper last month. Maybe we can find some ways of reducing the amount we are using."
2. make contact, connect or communicate with
can't get through on the phone, just can't get through to him
can refer to meaningful communication, such as advice