The basics are the same
Japanese scoreboards show the same information as American ones: innings across the top, runs per inning, and totals for runs, hits, and errors. The layout is familiar. The challenge is reading the Japanese characters.
Team name abbreviations
Each team is shown as a single kanji or short abbreviation. Here are the NPB teams:
Central League
巨 (Kyo) = Giants. 神 (Shin) = Tigers. De = BayStars. 広 (Hiro) = Carp. 中 (Naka) = Dragons. ヤ (Ya) = Swallows.
Pacific League
ソ (So) = Hawks. 日 (Nichi) = Fighters. オ (O) = Buffaloes. 楽 (Raku) = Eagles. 西 (Nishi) = Lions. ロ (Ro) = Marines.
Key scoreboard terms
回 (kai) = inning. 表 (omote) = top of inning. 裏 (ura) = bottom of inning. 安打 (anda) = hits. 失策 (shissaku) = errors. 投手 (toshu) = pitcher. 打者 (dasha) = batter.
The count display
Ball-Strike-Out is displayed as B-S-O, same as in America. The numbers are Arabic numerals (1, 2, 3), not kanji, so this part is easy to read.
Player names
Player names are shown in kanji on the scoreboard. Foreign players' names are written in katakana. You won't be able to read most of them, but the uniform number displayed alongside the name helps you match the scoreboard to the player on the field.
Speed gun
Pitch speed is shown in km/h, not mph. To convert roughly: multiply by 0.6. So 150 km/h ≈ 93 mph.
Tip
Take a photo of the scoreboard at the start of the game when you know the starting lineups. Use it as a reference throughout the game to match kanji names to jersey numbers.