"우리 할아버님의 성함은 가람이에요."
Translation:My grandfather's name is Garam.
When native Koreans speak, they are known to exhibit what's often referred to as "우리 mentality". Essentially, it means that when they speak about certain things, they'll do so in a collective sense rather than an individual sense as far as possession is concerned.
In contrast, in other countries, when people talk about their family members or possessions, the word "my" is used a lot. Native Koreans however, use the word "our" instead. For example: 1) Koreans don't usually say "my wife", they'll say "우리 아내" meaning "our wife". 2) Koreans don't usually say "my husband", they'll say "우리 남편" meaning "our husband". 3) Koreans don't usually say "my house", they'll say "우리 집/댁" meaning "our house". Keep in mind that this is true regardless of who the speaker is talking to.
Duolingo MODs, I think the context surrounding this sentence warrants an explanation of Korean culture or at least a review of it in the event that was discussed in a previous unit.
I hope this helps.