、。
She just watches the other kids playing without joining in herself.
Literal
She [topic-は] other [genitive-の] children [subject-が] play [nominalizer-の][object-を] just is-watching [only-だけで], from-self does-not-participate.
Two patterns to track. ただ~だけで is the 'just X-ing / only X-ing' frame, with ただ ('merely') reinforcing the limiter だけ. The whole phrase 見ているだけで means 'just watching, [and that's all].' 自分から ('of one's own accord, on her own') uses 自分 ('self') with the source-of-motion から — 'from self,' i.e., voluntarily/proactively. The contrast in the two clauses paints a picture of passive observation rather than active participation.