列車は１０時に出発したので、今ごろ大阪についているはずだ。

、。

The train left at 10:00, so it should already be in Osaka by now.

Literal

Train [topic-は] 10-o'clock [at-に] departed [because-ので], by-now Osaka [at-に] have-arrived [should-はず] [copula-だ].

Two clauses linked by ので. 今ごろ ('by about now, around this time') is a rough temporal expression. ついている is the resulting-state ~ている of 着く (arrive) — 'is in the state of having arrived' = 'is there.' The sentence stacks multiple inference markers: ので (cause), はず (logical expectation).