Connection
One login at one broker. It can hold several accounts.
Account
One tradeable account under a connection. Orders, positions and P&L are per account.
Strategy
A webhook plus its settings. Signals arrive at it; subscriptions decide who acts on them.
Subscription
One account following one strategy, with its own size and its own on/off switch.
Signal
One alert as received. It is recorded whether or not it produced an order.
Order
What was actually sent to the broker. One signal can produce several, or none.
Session
The trading day, rolled at 17:00 New York. Daily limits and trade counts reset there, not at midnight.
Flatten
Close everything open on an account or group, now, at market.
Blind
Tradeus cannot currently read the broker's state. What it does next depends on the feature — see the relevant page.