A currency pair expresses the price of one currency in terms of another. The first currency listed is the base; the second is the quote. The number shown is how many units of the quote currency one unit of the base currency buys.
Direction
A rising quote means the base currency is strengthening relative to the quote currency — it does not mean either currency is "going up" in isolation. Every move is a relative statement, which is why a pair can rise because the base strengthened, because the quote weakened, or both.
Pips, lots and value per move
The smallest conventional increment for most pairs is a pip, generally the fourth decimal place, with the notable exception of pairs quoted to two decimals such as those involving the Japanese yen. The monetary value of one pip depends on the position size and, for pairs where the quote currency differs from the account currency, on a conversion at prevailing rates.
Spread and session liquidity
The difference between bid and ask is a cost paid on entry. Spreads generally tighten in high-liquidity sessions and widen around session transitions, scheduled data releases and holidays. Analysis that assumes mid-price execution overstates results.
Cross rates
Pairs that exclude the US dollar are known as crosses, and their behaviour reflects the two underlying dollar pairs. This is why apparently unrelated dollar news can move a cross that does not contain the dollar at all.