。
She squeezed a few drops of lemon juice into her tea.
Literal
She [topic-は] honorable-tea [into-に] lemon 's juice [object-を] dropped.
御茶 (お茶) with the elevated 御 prefix (read as お in modern usage) is the standard polite word for tea — Japanese rarely uses 茶 alone in everyday speech. Note that 御 in this position is read お, not ご or おん; the same kanji has all three readings depending on context. レモンの汁 ('lemon juice') uses 汁 ('juice, broth, liquid'), the same kanji that anchors 味噌汁 ('miso soup'). たらす ('to drop, drip') is the transitive of 垂れる ('to hang, drip') — 'cause to drip.' The action implies a small, deliberate amount.