This question seems to come up in every edition of D&D and this version does not seem to really clarify the situation.
All of the spells of the type Conjure X (Animals, Celestials, Elementals, Fey) have text of the form:
The summoned creature[s] are friendly to you and your companions... They obey any verbal commands that you issue to them.
There's no indication about languages, but then Conjure Animals allows you to summon lots of creatures that have no languages at all. So it's not clear the spells would work at all unless you were granted magic communication ability as part of the spell.
Is it safe to assume that communication with Conjured creatures is automatic?
Are there notes outside of the spell that may indicate the requirement to know some special language?