Do the authors use credible evidence to support their findings? Are they allowing personal views or dubious information play a factor in their interpretations? Is their work legitimate, does it adhere to the standards of the field and does it make a meaningful contribution to the conversation in the field? These are all factors that experts within a discipline scrutinize before publishing an article.
Only journal articles are peer reviewed.
The term scholarly typically includes books published with an academic press, or a press otherwise embraced within a field of study.
This is a very nuanced evaluation you are being asked to do. Ask yourself: who wrote it, what expertise do they have in this field and what evidence do they use in their arguments?